Highly contoured components used in the aerospace industry including but not limited to frames, spars, ribs and stringers are typically made out of lightweight metal, such as aluminum. Metal fabrication processes such as, without limitation casting, forming, rolling and machining are well suited for fabricating highly contoured composite components with complex shapes. In spite of the trend toward replacing metal components with composites, few methods exist for fabricating continuous multi-leg shapes with complex contours that are needed for large commercial and military aircraft.
Existing methods for making highly contoured composite components are generally limited to hand layup techniques, braid/resin infusion fabrication, and the use of automated fiber placement (AFP) machines, however each of these techniques has disadvantages. For example, hand layup requiring manual placement of narrow bands of material into multi-leg shapes is both costly and time consuming, and may therefore only be suitable for prototyping activities and small production runs. Similarly, a known technique in which fibers are braided to form contoured shapes and then infused with resin is also time consuming and may produce components that exhibit qualities not suited to high performance applications, including added weight. Finally, the use of AFP machines may not be efficient for use in producing highly contoured, multi-leg components with tight radii because these structural features require the machine to start and stop and change direction relatively frequently. Moreover, certain component configurations such as those containing a Z or a J-cross section may not be fabricated using AFP machines because they may not be able to lay material in the inside corners of these components.
Accordingly, there is a need for a method of fabricating contoured and especially highly contoured, continuous composite structures containing multi-leg features that meet high performance specifications in a high volume production environment.